Moscow Blockchain Devs Meetup
Some Open Problems in Blockchains
Alexander Chepurnoy(aka kushti)@chepurnoyIOHK Research
Background
programming since 1996
p2p systems with Scala/Akka
Nxt core developer
Consensus Research
smartcontract.com cofounder(left)
Scorex since late 2014
IOHK Research
The talk is about
What are open problems in blockchains
How can we solve them
Current State
1.33 well understood systems working
Bitcoin
partly Ethereum
A lot of work-in-progress around
Bitcoin
highly centralized
scalability is questionable
well studied(in both theory & practice)
Troughput (TPS)
7 ??? no
2-3 in fact
1/600 in worse casehttps://www.reddit.com/r/Bitcoin/comments/3cgft7/largest_transaction_ever_mined_999657_kb_consumes/
Bitcoin Consensus Protocol
The Bitcoin Backbone Protocol:Analysis and Applications
Analysis of the Blockchain Protocol in Asynchronous Networks
Better PoW
Equihash - memory-hard PoW (ZCash)
Permacoin proofs of retrievability for static dataset
Rollerchain proofs of posession of state snapshots
Blockchain Pruning
Rollerchain
http://arxiv.org/abs/1603.07926
A Prunable Blockchain Consensus Protocol Based on Non-Interactive Proofs of Past States Retrievability
Rollerchain
Only last n full blocks to be stored collectively
and n state snapshots
Each miner stores k state snapshots
Rollerchain
New node can download a historical snapshot
Fullblocks not needed for mining could be thrown away
Blockheaders are to be stored forever, so must be small
Proof-of-Stake
Formalization is coming
Hopefully in 2016
Problems: randomness, forking, timing
Scalability
Move things off-chain
Sidechains
Avoid all the transactions execution(RsCoin)
Offchain
Lightning Network(ThunderNetwork)
Offchain contracts(SMC/SMP)
Smart Contracts
Ethereum isn't scalable
Hawk
Enigma
Anonymity
A lot of schemes proposed
Most of them are probably broken or not practical
Cryptonote
ZCash
Upcoming survey from Bernardo David
Applications
Randomness
System designs: The Blockchain as a Software Connector
Protocols study
Primitives
Post-quantum digital signatures: BLISS, NTRU
Trivial Things
Specially crafted database
Formalized code (not formal model)
Extensive testing at least :)
Conclusion
We have a lot of open problems!
A lot of results are to be released soon
Questions?
Twitter: @chepurnoyMail: [email protected]
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